Pressure casting machine



2 Sheets-Sheet 1 Filed Aug. 22 1966 INVENTOR. A L F RED NEF WWI MW drama/e74 Aug. 13, 1968 A. NEF

PRESSURE CASTING MACHINE 2 Sheets-Sheet 2 Filed Aug. 22, 1966 Fly. 2

'INVENTOR. ALFRED NEF United States Patent 3,396,873 PRESSURE CASTING MACHINE Alfred Nef, Uzwil, Switzerland, assignor to Gebruder Biihler A.G., Uzwil, Switzerland Filed Aug. 22, 1966, Ser. No. 574,087 Claims priority, application Switzerland, Aug. 25, 1965, 11,920/ 65 22 Claims. (Cl. 222309) ABSTRACT OF THE DISCLOSURE A pressure casting machine comprises a crucible for the smelt-heating of a metal to be cast and a conveying pump for conveying the smelt material from the crucible located within the molten metal. The conveying pump includes a housing with an inlet arranged below the level of the smelt material and a discharge feed conduit extending out of the crucible for discharge into a mold for casting or into a casting shot sleeve. A feature of the construction is that the piston which moves in the conveying pump housing is provided with a surrounding envelope of a material which is resistant to thermal and chemical action of the smelt material.

Summary of the invention This invention relates, in general, to pressure casting machines and, in particular, to a new and useful pressure casting machine having means for heating the smelt material and, which includes a piston pump mounted directly within the smelt material and to an improved construction of such pump.

At the present time, there are known pressure casting machines employing a piston pump as a means for conveying the material to be cast. In such a construction, identical material is employed for the cylinder and the massive conveying piston. Such a construction is advantageous because of the identical thermal expansions of these two parts. However, it has proved to be disadvantageous when oxidized smelt deposits on the conveying piston or its cylinder causes the locking of the conveying piston. In addition, in the event of a defect of the conveying piston, the latter must be exchanged entirely.

In accordance with the present invention, there is provided a construction in which the conveying piston which cooperates with a pump housing which is arranged directly within the smelt of the material to be pressure cast is provided with a metal core having a surrounding envelope or sleeve which is insensitive to smelt aggression and which is provided at a location around the piston which is within the range of the contact with the smelt.

Accordingly, it is an object of the invention to provide an improved pressure casting device which includes a conveying piston and cylinder pump construction for the material to be cast which includes a piston having a rigid metal core but with a surrounding envelope which is insensitive to smelt aggression.

A further object of the invention is to provide a pressure casting device which includes means for smelting the material to be cast including a crucible in which is located a pump for conveying the smelt material through ducts to a blast barrel and wherein the conveying pump is arranged directly within the smelt material in the crucible and includes an opening defined below the level of the smelt for the infced of the smelt material and a conveying passage for the material which extends from the pump to the blast barrel having passages of different flow cross section for improving the flow characteristics of the smelt.

A further object of the invention is to provide a pump 3,396,873 Patented Aug. 13, 1968 construction for conveying smelt in a casting machine which includes a conveying duct formed with a plurality of individual conveying duct portions including a vertical portion of relatively great cross section arranged vertically directly in the smelt of the material and a further conveying portion of a reduced cross section for increasing the velocity of the moving smelt when it is conveyed therethrough to the casting mold or blast barrel.

A further object of the invention is to provide a pressure casting device which is simple in design, rugged in construction and economical to manufacture.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

In the drawings:

FIG. 1 is a partial transverse sectional and partial elevational view of a pressure casting machine constructed in accordance with the invention; and

FIG. 2 is a section taken on the line IIII of FIG. 1.

Referring to the drawings, in particular, the invention embodied therein comprises a pressure casting machine which includes a smelt-housing 1 for accommodating a crucible 2 with a heater 4 arranged between the housing 1 and the crucible for heating the material to be cast to form a smelt 3. The crucible 2 is provided with a cover 10 having an aperture 11 to permit feeding of the material to the crucible which is to be cast.

In accordance with the invention, a conveying pump 5 for conveying the smelt or the molten material to be cast is supported from the cover 10 on brackets 18 to extend downwardly into the smelt 3. The pump 5 is made of a material which is insensitive to any chemical or thermal action of the smelt material and it includes a cylindical portion forming a pumping chamber 13 which is advantageously made of a porcelain material or a material having a porcelain coating. The pump also includes a vertical portion defining a vertical feed duct 16 of relatively large cross section, and a connecting duct 15 of slightly smaller cross section connects the feed duct with the pumping space or chamber 13. The pump 5 is advantageously formed of one unit formed with the passages 15 and 16 and with a widened opening portion 23 having an upper incoming feed duct 17 and a lower feed duct 14. The vertical feed chamber 16 is connected through a sleeve connection 25 to a feed duct member or conduit 26 having a bore 261 of much smaller cross section than the cross section of the vertical feed duct 16. The feed duct 26 is arranged so that material may be pumped from the pump 5 to a blast barrel 6, the blast barrel 6 is provided with an opening 7 for receiving the material and a funnel element 8 is provided around the blast barrel 6 to guide the smelt material into the barrel. The intermediate connecting sleeve 25 is of slight wall thickness and small length in relation to the measurements of the feed duct 26 and the feed duct 16. All of these duct elements consist of a material which is chemically and thermally insensitive to the pressure casting smelts.

The material is conveyed from the pump chamber 13 through the ducts 15, 16 and 261 to the blast barrel 6 by means of a piston generally designated 20. A feature of the construction is that the piston is provided with a metal core 201 but within the range of contact of the piston with the smelt material 3, there is provided an exchangeable envelope or sleeve 202. The sleeve 202 is insensitive to smelt aggression and is perferably made of a graphite having a cement bottom 203 built therein. The envelope 202 is held against the metal core 201 by an elastic pipe or sleeve 204, which is ararnged at the upper end of the core 201 and secured thereto by a nut 205. A packing 206 for the protection of the thread on the piston and the protection of the nut 205 is provided at the upper end of the piston metal core 201.

The piston is coupled by a couple pin or clutch member 208 with a piston rod 32 which includes a piston portion which slides in a hydraulic operating or actuating cylinder 52. In accordance with the further feature of the invention, the operating cylinder 52 is mounted in an adjustable manner on support columns 301, 302 and 303 between adjustable threaded nut members 38 and 39. The cylinder plate 31 is provided with notches 312 and 313 which permit the end of the plate to be swung outwardly from the support columns 302 and 303 on the column 301 for easy access to the piston 20 after it has been disconnected from the rod 32.

A further feature of the construction is the provision of a stop mechanism for limiting the movement of the piston 20 in each direction. The stop mechanism includes an impact plate 33 which is secured to the piston rod 32 and which permits movement of the piston rod 32 with the piston 20 between two end positions defined by a stop plate 35 and a stop plate 36. Stop plate 35 includes a hub portion 351 which may be vertically and horizontally adjustably positioned in respect to the supporting column 301 and clamped at an adjusted location. Upper stop plate 35 carries the plate 36 on the ends of adjustable bolts or supporting arms 361. Adjusting wing nut 362 may be threaded on the supporting bolts 361 for the purpose of changing the spacing between plates 35 and 36.

Also indicated in FIG. 1 is a schematic representation of a hydraulic control for the operating cylinder 52. The control includes a hydraulic pump 50 connected to a four-way valve 51 which connects, in turn, through conduits 57 and 58 to respective alternate sides of the piston within the cylinder 52. The four-way valve 51 is electrically actuated from a power supply 48 by means of a control 40 which is connected to selectively operate control solenoids 41 and 42 for the purpose of regulating flow through a conduit 56 extending from the pump to the control valve 51 and a conduit 59 for returning liquid 54 to a reservoir 53. The pump also takes suction from the reservoir 53 through a conduit 55. Actuation of the respective solenoids 41 and 42 is effective to shift the connecting valve between the connection from the conduit 56 to the conduit 58 and from the conduit 57 to the conduit 59 as indicated in FIG. 1 to a connection in which the conduit 56 connects directly to the conduit 57 and the conduit 58 connects directly to the conduit 59. The control 40 is advantageously combined in a control system for regulating the operation of the pressure casting device.

The operation of the device is as follows: In the indicated position of the electro-hydraulic control, the hydraulic pump 50 will convey the hydraulic medium 54 from the tank 53 through the suction line 56 and the four-way valve 51 into the feed pipe 58 and the hydraulic cylinder 52. Therefore, the piston inside the hydraulic cylinder 52, which is not shown, is lifted with the piston rod 32 and the piston 20. The lifting motion will be stopped when the impact plate 33, which is afiixed to the piston rod 32, hits the upper stop 35. Because the upper stop 32 as well as the spacing between the upper and lower stops may be easily adjusted, the stroke of the piston may be correspondingly adjusted. The stop plate 35 is provided with a curved slot 32 which permits the plate to be swung outwardly away from the piston 20 when the piston is to be removed, for example.

As indicated in FIG. 1, the smelt 3 will remain at the same level above the cylinder space 13 and in the feed duct 16. The control 40 is then actuated to energize the coil 41 to shift the four-way valve 51 from the connection indicated to one in which the conduit 56 connects the conduit 57 and the conduit 59 connects the conduit 58. The pump 50 will then convey hydraulic medium 54 through the feed pipe 57 and into the upper 4 pressure chamber inside the hydraulic cylinder 52 to cause the piston 20 to be moved downwardly. The hydraulic medium from the lower pressure chamber will be delivered back through the return conduit 58 and the conduit 59 to the reservoir 53.

The downward movement of the piston 20 causes first the closing of the feed aperture 14 so that no more smelt 3 can flow into the pumping chamber 13 and the smelt material which is in the chamber 13 will be forced through the passages 15, 16 and 261 into the opening 7 of the blast barrel 6. The downward motion of the piston 20 will be limited by contact of the plate 33 with the stop 36. When the piston stroke is ended, the magnet coil 41 is de-energized and the magnet coil 42 is excited. This causes the four-way valve to be reversed again so that the hydraulic pump again conveys the hydraulic medium 54 from the suction pipe 55 and pressure 56 into the feed pipe 58 to cause the lifting movement of piston 20 once again. During the lifting movement, the feed apertures 14 are thereby opened and the smelt 3 may flow back into the crucible 2.

The inventive device provides many advantages in operation and construction over the prior art. The construction is such that the upper edge of the chemically and thermically insensitive envelope 202 which surrounds and protects the metal core 201 of the piston 20 will be located so that no possibility of the smelt material contacting this core is possible. In a preferred arrangement, a graphite soft material is provided for the envelope 202 and a porcelain hard material is provided for the pump housing 5. The clearance between the piston and the pump housing and the envelope 202 and the housing can be maintained very small. Any smelt impurities which are apt to deposit will be left on the soft envelope 202 of the piston 20 and this envelope may be easily exchanged for a new one should the accumulation become excessive.

A further feature of the piston construction is that the elastic sleeve 204 is easily fixed to the upper end of the piston core 201 by means of nut 205 so that the lower envelope 202 will be permitted to expand and will not be subject to stresses for this reason.

The pump housing is advantageously made up of a unitary block construction so that it will be insensitive to fractures and will not have any points of temperature gradients which will cause any thermal stresses.

A further feature of the pump construction is that the supply duct 26 having the small-sized bore 261 and being of a thick wall construction will permit conveyance of the smelt material to the blast barrel 6 without any danger of smelt freezing. The relatively large cross section of the feed duct 16 permits relatively large volume in this space whereby a good heat capacity of the smelt may be retained. A relatively small flow cross section of the duct 15 and supply duct 26 permits greater flow velocity with each pump stroke and thus creates the alleviation of the adherence of any large amounts of smelt to the duct walls. Even the danger of rapid freezing is essentially eliminated. When the pump stroke during the back motion of the piston has been eifected any freezing danger will be alleviated because the smelt from the highest point of the supply duct 26 flows back rapidly into the feed duct 16 which provides a volume of large heat capacity.

The adjustable operation of the stroke of the piston is very advantageous and the stops for providing such adjustment may be easily positioned.

By arranging the pump 5 within the smelt 3, it is insured that the piston 20 will be maintained at constant temperature both at the location above and below the lower end of the envelope 202. In addition, because the pump is located in this smelt, there is no danger of any leakage losses. By mounting the stops so that they can be easily removed from the operating position, it is possible to obtain complete access to the piston and all of the other operating parts of the pump.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. A pressure casting machine comprising, a crucible for smelt-heating the material to be cast, a conveying pump for conveying the smelt material out of the smelt crucible, said conveying pump including a pump housing adapted to be arranged in the smelt of said crucible and having a pump chamber adapted to be exposed to the smelt material, a feed conduit connected to the pump chamber for conveying material to the location of casting, and a piston slidable in said pump chamber for directing the smelt through the feed conduit, said piston having a metal core with a loosely fitted surrounding envelope of a material resistant to the thermal and chemical actions of the smelt material, said envelope being located at least over the area of the piston which is adapted to contact the smelt material.

2. A pressure casting machine, comprising a crucible for smelt-heating the material to be cast, a conveying pump for conveying the smelt material from the smelt crucible to the location of casting, said conveying pump including a pump housing adapted to be arranged in the smelt of said crucible and having a pump chamber adapted to be exposed to the smelt material, a feed conduit connected to the pump chamber for conveying material to the location of casting, a piston slidable in said pump chamber for directing the smelt through the feed conduit, said piston having a metal core with a surrounding envelope of a material resistant to the thermal and chemical actions of the smelt material, said envelope being located at least over the area of the piston which is adapted to contact the smelt material, and means elastically holding said surrounding envelope to said metal core of said piston.

3. A pressure casting machine, comprising a crucible for smelt-heating the material to be cast, a conveying pump for conveying the smelt material from the smelt crucible to the location of casting, said conveying pump including a pump housing adapted to be arranged in the smelt of said crucible and having a pump cham ber adapted to be exposed to the smelt material, a feed conduit connected to the pump chamber for conveying material to the location of casting, and a piston slidable in said pump chamber for directing the smelt through the feed conduit, said piston having a metal core with a surrounding envelope of a material resistant to the thermal and chemical actions of the smelt material, said envelope being located at least over the area of the piston which is adapted to contact the smelt material, said piston comprising an elongated metal core, said envelope being of a material resistant to the thermal and chemical actions of the smelt material and surrounding the lower portion of said core, a flexible sleeve connecting said envelope at one end and surrounding said metal core adjacent its upper end, and a fastening nut secured to said piston adjacent its upper end holding said flexible sleeve to said piston.

4. A pressure casting machine, according to claim 3, including a packing disposed between said nut and said piston core.

-5. A pressure casting machine, according to claim 4, wherein said packing extends around said nut and protects said nut and is disposed between said nut and said piston core, said nut being threaded onto said piston core.

6. A pressure casting machine, according to claim 1, wherein said surrounding envelope is made of a graphite material.

7. A pressure casting machine, according to claim 1, wherein said pump housing is made of a porcelain material.

8. A pressure casting machine comprising a crucible for smelt-heating the material to be cast, a conveying pump for conveying the smelt material from the smelt crucible to the location of casting, said conveying pump including a pump housing adapted to be arranged in the smelt of said crucible and having a pump chamber adapted to be exposed to the smelt material, a feed conduit connected to the pump chamber for conveying material to the location of casting, and a piston slidable in said pump chamber for directing the smelt through the feed conduit, said piston having a metal core with a surrounding envelope of a material resistant to the thermal and chemical actions of the smelt material, said envelope being located at least over the area of the piston which is adapetd to contact to the smelt material, said pump housing including an upper widened portion above said pump chamber which is opened on the interior for said crucible, said pump housing including a side opening therein at the location of the smelt material for permitting the infeed of smelt material, said piston including at least a portion having a diameter of substantially the same size as said pump chamber to permit easy sliding movement therein.

9. A pressure casting machine, according to claim 1, including means for moving said piston connected to the upper end thereof, first and second adjustable stops positioned in the path of movement of said piston and located to contact and limit the end of the movement of the piston in each direction, and means for mounting said stops to permit adjustment thereof.

10. A pressure casting machine comprising a crucible for smelt-heating the material to be cast, a conveying pump for conveying the smelt material from the smelt crucible to the location of casting, said conveying pump including a pump housing adapted to be arranged in the smelt of said crucible and having a pump chamber adapted to be exposed to the smelt material, a feed conduit connected to the pump chamber for conveying material to the location of casting, and a piston slidable in said pump chamber for directing the smelt through the feed conduit, said piston having a metal core with a surrounding envelope of a material resistant to the thermal and chemical actions of the smelt material, said envelope being located at least over the area of the piston which is adapted to contact the smelt material, means connected to the upper end of said piston for moving said piston in said pump chamber, a supporting column, a first stop mounted on said supporting column and being adjustably movable therealong for varying the height thereof, and a second stop member connected to said first stop member by means permitting a change in the spacing of said first and second stop members, said stop members being adapted to be located in the path of movement of said piston and limiting the end movements of said piston in each direction.

11. A pressure casting machine, according to claim 10-, where-in said stop members are pivotally mounted so that they may be shifted out of the way of said piston.

12. A pressure casting machine comprising a crucible for smelt-heating the material to be cast, a conveying pump for conveying the smelt material from the smelt crucible to the location of casting, said conveying pump including a pump housing adapted to be arranged in the smelt of said crucible and having pump chamber adapted to be exposed to the smelt material, a feed condition connected to the pump chamber for conveying material to the location of casting, and a piston slidable in said pump chamber for directing the smelt through the feed conduit, said piston having a metal core with a surrounding envelope of material resistant to the thermal and chemical actions of the smelt material, said envelope being located at least over the area of the piston which is adapted to contact the smelt material, a cover on said crucible, a supporting column mounted on said cover, an opening defined in said cover through which said piston extends, 'a cylinder plate supported on said column and being adjustably movable therealong for varying the height thereof, an actuating cylinder for moving said piston disposed on said cylinder plate and including a connecting rod connected to said piston for shifting said piston, and means supporting first and second stop members on said column in an adjustable position along the path of movement of said piston and being arranged to block further movement of said piston in each direction in order to limit the stroke thereof, said cylinder plate and said stops being mounted for swinging movement in respect to said supporting column.

13. A pressure casting machine, according to claim 1, wherein said feed conduit includes means in said pump housing defining an ascending duct connected to said pump housing, said pump housing being a single unit which also defines said pump cylinder.

14. A pressure casting machine, according to claim 13, including a connecting duct connected between said pump chamber and said ascending duct which is of smaller cross section than said ascending duct.

15. A pressure casting machine, according to claim 14, including a feed duct connected to the upper end of said ascending duct, said feed duct being of smaller cross section than said ascending duct.

16. A pressure casting machine, according to claim 1, wherein said feed conduit includes an ascending duct portion, a connecting duct portion connecting said ascending duct portion with said pump chamber, and a feed duct portion connecting said ascending duct portion at one end and extending outwardly therefrom and terminating in a discharge opening for discharging the smelt material to a location of casting, said feed duct being of smaller cross sectional area than said ascending duct.

17. A pressure casting machine, according to claim 16, wherein said feed duct portion has a smaller cross section area than said connecting duct portion, said connecting duct portion being smaller in cross section than said ascending duct portion.

18. A pressure casting machine, according to claim 1, wherein said pump housing includes an ascending duct defined therein, and a connecting duct connected between said ascending duct and said pumping chamber, a feed duct extending outwardly from said pump, and a connecting sleeve member connecting said feed duct and the upper end of said ascending duct, said sleeve member being of a slight wall strength and relatively short length in relation to the dimensions of said feed duct and said ascending duct.

19. A pressure casting machine, according to claim 1, wherein said pump housing includes an Opening in a Wall thereof within the range of movement uncovered when said piston is moved to its uppermost position of its stroke.

20. A pressure casting machine comprising, a crucible housing, a crucible supported within said housing, heater means in said housing for heating materials in said crucible to form a smelt, a unitary pump disposed in said crucible and adapted to be located with at least a lower portion below the level of the smelt, said pump having a pumping chamber which is opened at its upper end, said pump having an ascending duct portion extending substantially parallel to said pumping chamber and a connecting duct connected to the lower end of said pumping chamber and said ascending duct, a feed duct connected to the upper end of said ascending duct and eX- tending outwardly from said crucible, a piston slidable in said pump cylinder having at least a lower portion thereof substantially the same diameter as the lower portion of said pump chamber, said pump housing having an opening extending through a wall thereof into communication with said pump chamber at a location to be uncovered by said piston at the uppermost location of the stroke thereof, a column mounted over said crucible, a cylinder plate adjustably positioned on said column, an actuating cylinder carried on said cylinder plate and including a piston rod with a piston thereon movable within said actuating cylinder, said piston rod being connected to said conveying piston for moving said piston, means for selectively pressurizing said cylinder on opposite sides of said actuating piston for shifting said conveying piston in said pump cylinder, and adjustable stop means mounted on said column and being adapted to be located in the path of movement of at least a portion of said piston to limit the movement of said piston in each direction for fixing the stroke thereof.

21. A pressure casting machine, according to claim 20, wherein said ascending duct is of greater cross section than said connecting duct.

22. A pressure casting machine, according to claim 20, including a thin wall connecting sleeve connected between said ascending duct and said feed duct, and wherein said feed duct includes a flow cross sectional area which is smaller than connecting duct and said ascending duct.

References Cited UNITED STATES PATENTS 1,595,783 10/1926 Howes 222385 X 2,835,005 5/1958 Green 222385 2,485,526 10/1949 Bennett 103-216 3,048,384 8/1962 Sweeney et al 103-1 14 3,093,087 6/1963 Hansen 1032l6 3,255,702 6/1966 Gehrm 103-114 ROBERT B. REEVES, Primary Examiner.

HADD S. LANE, Assistant Examiner. 

